GraphQL relations

I'm following the tutorials of Academind, so this video is my current standpoint: https://www.youtube.com/watch?v=MRrcUQhZwBc

So my current code is:

const express = require('express');
const bodyParser = require('body-parser');
const graphqlHttp = require('express-graphql');
const { buildSchema } = require('graphql');
const mongoose = require('mongoose');
const bcrypt = require('bcryptjs');

const Event = require('./models/event');
const User = require('./models/user');

const app = express();

app.use(bodyParser.json());

app.use(
  '/graphql',
  graphqlHttp({
    schema: buildSchema(`
        type Event {
          _id: ID!
          title: String!
          description: String!
          price: Float!
          date: String!
        }

        type User {
          _id: ID!
          email: String!
          password: String
        }

        input EventInput {
          title: String!
          description: String!
          price: Float!
          date: String!
        }

        input UserInput {
          email: String!
          password: String!
        }

        type RootQuery {
            events: [Event!]!
        }

        type RootMutation {
            createEvent(eventInput: EventInput): Event
            createUser(userInput: UserInput): User
        }

        schema {
            query: RootQuery
            mutation: RootMutation
        }
    `),
    rootValue: {
      events: () => {
        return Event.find()
          .then(events => {
            return events.map(event => {
              return { ...event._doc, _id: event.id };
            });
          })
          .catch(err => {
            throw err;
          });
      },
      createEvent: args => {
        const event = new Event({
          title: args.eventInput.title,
          description: args.eventInput.description,
          price: +args.eventInput.price,
          date: new Date(args.eventInput.date),
          creator: '5c0f6dcde049d205fa2471dc'
        });
        let createdEvent;
        return event
          .save()
          .then(result => {
            createdEvent = { ...result._doc, _id: result._doc._id.toString() };
            return User.findById('5c0f6dcde049d205fa2471dc');
          })
          .then(user => {
            if (!user) {
              throw new Error('User not found.');
            }
            user.createdEvents.push(event);
            return user.save();
          })
          .then(result => {
            return createdEvent;
          })
          .catch(err => {
            console.log(err);
            throw err;
          });
      },
      createUser: args => {
        return User.findOne({ email: args.userInput.email })
          .then(user => {
            if (user) {
              throw new Error('User exists already.');
            }
            return bcrypt.hash(args.userInput.password, 12);
          })
          .then(hashedPassword => {
            const user = new User({
              email: args.userInput.email,
              password: hashedPassword
            });
            return user.save();
          })
          .then(result => {
            return { ...result._doc, password: null, _id: result.id };
          })
          .catch(err => {
            throw err;
          });
      }
    },
    graphiql: true
  })
);

mongoose
  .connect(
    `mongodb+srv://${process.env.MONGO_USER}:${
      process.env.MONGO_PASSWORD
    }@cluster0-ntrwp.mongodb.net/${process.env.MONGO_DB}?retryWrites=true`
  )
  .then(() => {
    app.listen(3000);
  })
  .catch(err => {
    console.log(err);
  });

I have currently created events with a relation to a user. Now I want to get all events from a user. Therefore I've found this article: https://devhints.io/graphql I want to use the "Lookups", so my code for a request would be:

{
  events(_id: "5da717be4330150430fd770e") { _id }
}

But I am recieving this error:

{
  "errors": [
    {
      "message": "Unknown argument \"id\" on field \"events\" of type \"RootQuery\".",
      "locations": [
        {
          "line": 2,
          "column": 10
        }
      ]
    }
  ]
}

But what do I need to do to get it working?

from GraphQL relations